#include <QCoreApplication>

#include <iostream>
#include <cstdlib>
#include <math.h>
using namespace std;
int main(int argc, char ** argv)
{
  int T , a , c , h , s;
    a = 1; c=a* sqrt (2) ; h= c/2; s=c*(h/2);
  cout << "number 1 - 4: ";
  cin >> T ;

  switch (T)

    {
          case 1: cout << a ;break;
          case 2: cout << c ;break;
          case 3: cout << h ;break;
          case 4: cout << s ;break;
          default: cout << "error";break;
    }



    return 0;
}
